A screen device has been widely known in that a screen is wound around a winding shaft having a coil spring as a power source while an open/close operation frame is attached at the extremity of the screen for automatically winding the screen.
In such an automatic winding-up screen device, the screen is wound by a rotational urging force due to the swinging of a coil spring, so that the winding speed is increased upon completion of the winding, and the operation frame attached to the extremity of the screen produces a large impact upon colliding with a winding box, making a large collision sound. In order to minimize this problem, a damper is normally provided to control the increase in winding speed (see, for example, Japanese Unexamined Patent Application Publication No. 2003-106076).
In the damper of this conventional screen device, the rotational force of the winding shaft is always transmitted to the damper regardless of the rotational direction of the winding shaft. By use of a one-way clutch housed in the damper, a damper resistance is applied when the screen is wound around the winding shaft, while no resistance is applied when pulling the screen down.
However, since the one-way clutch houses the damper, when the winding shaft is rotated in the direction to pull down the screen, a slight resistance is still applied to the screen retracting operation. For example, in the case of an oil damper, there is frictional resistance between a rubber seal to prevent oil from leaking and a shaft penetrating the seal, thereby making it more difficult to pull down the screen.
Also, since the damper is designed to reduce the winding force of the coil spring for winding the screen, the winding force is significantly reduced when wind is acted on the screen, for example, in comparison with devices without dampers, so that pulling down the screen may be difficult to be conducted depending on the circumstances.